Construction of steam-engines



N.FETERS. PHOTO-LITHGRAPHER, WASHINGTON. D. C.

NA'IHANIEL` BOSWORTH, OF PHILADELPHIA, PENNSYLVANIA.

Specification of Letters llatent No. 824, dated July 9, 1838.

To all whom t may concern.'

Be it known that I, NATHAMEL BoswoRTH, of the city of Philadelphia,inthe State of Pennsylvania, Vhave invented cert-ain Improvements in theManner of Constructing Steam-Engines; and I do hereby` declare that thefollowing is afull and exact description thereof.

My first improvement consists in the manner in which I construct landset the boiler or boilers and connect them with ,the` pipes for theconveyance of steam, and the auxiliary parts of the engine. The boilerswhich I employ are of the cylindrical kind, and they are to be so -set`as that they may be completely `surrounded by the flames and heated airfrom the fire, and have their Awhole surface, therefor, converted into afire surface, instead of exposing one half, only, of the boiler, to thedirect action of the heat as is usually the case. It is well known that,`even where t-he best precautions are used to prevent it, a largeportion of heat is lost by radilication, from that part of the boilernot exposed to the fire; a loss which is entirely obviated by my plan,as the boiler is, over its whole surface, made a recipient of heat, bybeing constantly encompassed by a medium hotter than itself. It has beensatisfactorily ascertained that thisview of the subject is not a matterof theoryv only,

but that the quantity of steam produced byV the combustionof a givenquantity of fuel, is much increased byl this arrangement. These boilers,as they are to be entirely surrounded by the fire, are to be keptcompletelyfull of water, land are not, therefore, subject to burn out. fa y Figures 1 and 2 in the accompanying drawingrepresent the form of theboilers, and the mode of sett-ing them, as shown in Fig. 1, two or moreboilers are supposed to be used, placed side by side. y

A, A, shows one of the boilers, in section. These boilersare to be soset as to form a considerable angle with the horizon, rising from theirfront toward their back ends,`

abut one inch in a foot; `by which elevation the steam willV be causedto escape readily from the boiler into the steam chamber or receiver atits upper end.

B, B, is the receiver, and is connected with the force pump; the dottedline I) being the water line, at the level of the upper edge of theboiler; the space above D being the steam chamber. Y E 1s a water pipeconnecting "the boiler C, a steampipe connectingthe top of the boiler`with the steam chamber.` 1 i F 1s the re place, and G the ash pit; Il,

H, the open space surrounding the boiler, y

Vwith the lower part of the receiver; andC, w

and I the flue leading to the chimney. .The Y steam pipes to conduct thesteam `from the receiver to the cylinder, should not enter the pipes C,C, but should, in all cases open into the top of the receiver betweenthese pipes. IVhen the steam chamber and connec- 1 x p tions are thusarranged, it will be found that there is a `complete separation of :thewater from the steam which may be intermiXed` in` passing from theboilers to the receiver.

\ When a single boileronly is wanted, itis '5 tof be set in the samemanner as when two or moreboilers are employed, but lnstead of thereceiverwhich 1s used to connect several boilers, I make a steam chamberin theman- H; 4

ner shown iny Fig. 2 where A,\A,` isthe boiler, and B, B acontinuationthereof, rising vertically. The dotted line D, is the waterline, Hthe steam pipe leading to the i cylinder,- I, the water supplypipe, and K the safety valve.

The steam cylinder, with its stuffing box, and piston, represented invFig. 3, has nothing in it peculiar excepting the construction ofthepiston, which is ma eof metal Ain one piece Vand withoutv packing. "Itmay be formed of hard cast-iron, o-r of cast steel, and must be finishedperfectly true and smooth. Its diameter is to be such thatwhen itstemperature is raised one hundred degrees above that of the cylinder, it.will still'pass through it readily, but leaving no sensible spacebetween t-he two; when of the vsame `temperature with the cylinderitwill of course pass through it loosely. U to a diameter of four inchesI think it leave the piston perfectly solid, but if above this size itmay be made hollow, for the purpose of decreasing its weight. Such apisparent friction beyond that which necessarily exists in the passingof the piston rod through the stuffing box, and the most carefulobservation leads to the conclusion that there is not any loss of steambetween the est to `ton I have found to work without any apy pistonandthe cylinder andif there is any,

C is intended to illustrate the principle upon which the valve operates.That which characterizes this valve is its being so con Y structed as topossess the property of'shutting oif the steam at a half or any othergiven part of the stroke, this effect resulting from the relativeproportion of its respective parts, without its being complicated by 1any addition thereto.V The ordinary value,

moved by an eccentric, is usually made wwithout reference to anyparticular proportion between the face of the valve andthe steam Ypassages, the eccentric being set at right angles or nearly so, to thecrank, constituting what is usually termed a whole stroke valve, lettingthe steam on soon after passing the center on one side of the piston,the steam which caused the preceding stroke escaping simultaneously, ornearly so. The valve shown in Fig. 4, is so proportioned as to shutoffat half stroke; which is eifected, first, bythe proportion between thevalve faces and the induction passages which they Y alternately cover,without regard to the center passage; and secondly, by the peculiarposition in which the eccentric is set to the cranks, this in theinstance given, being forty five degrees from the line of the crank,

instead of ninety; and as much less, or nearer to the line of the crank,when the proportion is altered so as to shut olf at one third, y

or one fourth of thel stroke.

The valve as shown in the drawing, is supposed to be moving in thevdirection Yof the exceeding in distance the extreme of variaarrow and tohave accomplished threefourths of its motion, measuring on the cirlcumference of the diagram (c) from a to b the crank having just passedthe center, and the piston being moving in the same direction with thevalve, is in the act `of receiving i steam as will be seen by inspectingthe valve. This motion of the valve being confrom b to c; the motion ofthe valve will middle, or eduction passage.

nection between the eccentric and the valve; but this is of noconsequence to the understanding of the operation provided it be bornein mindV that the valve and piston are supposed to be moving in thedirection of the arrow. The stroke of the piston being completed, a likeeect will be produced in that which succeeds it in the oppositedirection. It will be seen by inspecting the diagram C, that the steamis leton the pistonV Yduring the course of one fourth of the entirecircle, as from c to cl; the peculiar properties of this valve beingderived fromthe quadrature of the circle. i

To arrange the valve to shut off at a third of the'stroke, there needsno other change than an addition at each end of the valve, correspondingwith the distance, or space, from e to f, and a slight difference insetting the eccentric a little forward, so as to permit 'the valve toopen when the crank is on, or a little past the center. It will beobserved, in this latter case, that the size of the steam passage willVbe diminished beyondY the numerical proportion, but it is also toV bereco-llected that the piston, when near the center, is moving at acomparatively slow rate; and the'speed will be found, by calculation, orupon inspection, to be in the exact ratio ofthe diminution of thepassage.

Fig. 5 represents my improved water in* dicator which shows the heightof the water in the boiler, by means of a glass tube of the usual form,butk so arranged as not to become heated by the steam or water. of theboiler. C, C is a water pipe connecting the llower part of the boiler Awith the 4glass indicator tube D; and B lB is a tube connecting thesteam chamber with the upper'end of said glass tube. The water tube C, Cis bent down at X, in the manner shown in the v drawing, a descent beinggiven to this bend the boiler cannot descend sov as to mingle 1 with thewater in the leg i Y, and consequently the water in this leg, in thetube C, and in the glass indicator, must be kept at a temperature butlittle, above that of the sura rounding atmosphere; the only' heatingtinuous will be completed on its arrivalY at the place of the dottedline on the right,E while the motion of the eccentric will be;

cause to which it issubjected being from the conducting power of thetubes; and the water produced by the condensation of the smallk portionof steam which rst enters the tube B. The length of the tube B, as drawnin the figure, is six feet; four feet ofY it, next toward the glassbeing half an inchl in diameter, and two feet of the portion B, next tothe boiler, being two inches in diameter; the proportion being such thatwhen all the atmospheric air in the portion B, is driven into the halfinch tube B, the pressure will be equal to 240 lbs. to the square inch;the steamtherefore, cannot nd its way into the smaller tube, and as airwill not conduct heat downward into the indicator, it must remaincomparatively cold, while is performs its oiiice perfectly; Vthere notbeing any apparent tendency inthe steam and air to intermingle. v

It will be proper to remark that what I have called the receiver diEersessentially from what is usually denominated a steam drum, the oce ofthe latter being that of a steam chamber only, while my receiver is.always to contain water to the same height in which it exists in theboiler, with which it is connected for that purpose; this vessel, in myengine, receiving also the requisite water from the supply, or forcepumpsyits construction for the purpose of performing these respectiveoices, give to it a character essentially new, distinguishing it Yfromthe ordinary steam drum in a manner which must be perfectly apparent.

In the improvements above described `I have had in view mainly, toattain a higher degree of speed than has hitherto been thought eligiblein the reciprocating engine.

It is now an admitted law in mechanics, thatfriction is as the time; andit is mani-V fest, therefore, that if'an engine can beso. constructed asgreatly to decrease the weight :of its moving parts, and greatly toincrease the speed with which it moves, there must,

from the saving of resistance from friction, alone, be very importantadvantages ob` tained. I have succeeded in practice, in

working the piston of my engine at a speed of upward of two thousandfeet per minute,

and have thus produced e'ects at least five` fold greater than has ever,heretofore, been produced by engines of the same weight.

I am aware that I cannotclaim the increased speed of which my enginesadmit, in the abstract; but I do claim it in combina- 3. I claim theconstructing of a metallic piston, to move without friction inthe mannerset forth. I do not claim to be the first to have used a solid metallicpiston; but I do claim to be the first who has used it so asto passthrough the cylinder without friction; having been the first toAascertain that this might be done without a waste of steam. 4. I claimthe manner of constructing and using the receiver, when two or moreboilers are employed,.as herein fully made known.

5. I claim the manner in which I haveconstructed my indicator andconnected and combined the same with the boiler substantially asdescribed lastly.

6. I claim -the particular construction of the slide valve as set forthfor cutting off the steam at any designated part of the stroke of thepiston; this result being obtained bythe particular proportion of itsparts `without resorting to any greater complexity of construction thanin the ordinary whole stroke valve.

NATHL., BOSWORTH.

Witnesses L. BANGER, JUDAH DoBsoN.

